Embossed thermoplastic resin sheets in which a large number of minute projections and recesses (embossment) are formed on surfaces of thermoplastic resin sheets are widely used as interlayer films for laminated glass and for other applications. For example, a large number of minute projections and recesses are formed on a surface of an interlayer film for laminated glass for the purpose of preventing blocking between films, improving handleability thereof upon stacking of a glass sheet and the interlayer film (slipperiness between the film and a glass sheet), and enhancing deaeration upon lamination of the film and the glass sheet. Particularly, in a case where the recesses among the recesses and the projections have a groove shape with a continuous bottom (hereafter, also referred to as “recesses in the shape of engraved lines”) and are regularly arranged side by side in parallel with one another, such a sheet can exhibit significantly excellent deaeration properties (see Patent Literature 1, for example).
However, use of such an embossed thermoplastic resin sheet as an interlayer film for laminated glass causes optical distortion in the resulting laminated glass, resulting in poor visibility.
Even in the case of a thermoplastic resin sheet on which recesses in the shape of engraved lines are regularly arranged in parallel with one another, the sheet used as an interlayer film for laminated glass may fail to exhibit its deaeration properties sufficiently depending on the shape of the surface or conditions for lamination of the sheet with a glass sheet during production of laminated glass.